In recent years, an air bag device has become prevalent as a safety device for occupant protection that protects an occupant from impact when a vehicle undergoes a collision. The air bag device has the function of quickly expanding in a space between the occupant and an interior structure during collision, and absorbing the impact when the occupant directly collides with an instrument panel, a side door, a handle, or the like. Thus, in general, the air bag device includes a sensor that detects a sudden deceleration when receiving impact such as collision of a vehicle, an inflator that produces high pressure gas for expansion in response to reception of a signal from a sensor, an air bag body that expands, and deploys using high pressure gas for expansion from the inflator so as to reduce impact on an occupant, and a diagnostic circuit that determines whether or not an air bag system is functioning normally.
Also, in recent years, many vehicles provided with curtain airbags that expand and deploy along the side surfaces of the vehicle in the vehicle interior have been used in order to protect the head of an occupant in an accident such as a side collision accident against a vehicle or a rollover (for example, Patent Literature 1). This curtain air bag operates as follows. Specifically, when the occurrence of an accident such as a side collision accident against a vehicle or a rollover is detected, or when the occurrence of these accidents is predicted, inflation gas ejected from an inflator flows into the curtain air bag, and expands and deploys the curtain air bag.
In order to absorb impact on the head of the occupant, this curtain air bag needs to hold the inner pressure for a long period of time such as several seconds while the vehicle is rolling over, and in order to increase the airtightness of the air bag, sewing portions of the curtain air bag are often sealed using a sealing material so as to increase the airtightness. For example, when two base cloths are stacked and sewn, a sealing material that is to adhere to a synthetic resin is applied along a sewing line.